Merge pull request raviprakashdev#69 from min0o/master

raviprakashdev · web-flow · commit a50f7300dcfd · 2020-10-28T00:58:36.000+05:30
Create 8queens.py
diff --git a/8queens.py b/8queens.py
@@ -0,0 +1,28 @@
+BOARD_SIZE = 8
+
+class BailOut(Exception):
+    pass
+
+def validate(queens):
+    left = right = col = queens[-1]
+    for r in reversed(queens[:-1]):
+        left, right = left-1, right+1
+        if r in (left, col, right):
+            raise BailOut
+
+def add_queen(queens):
+    for i in range(BOARD_SIZE):
+        test_queens = queens + [i]
+        try:
+            validate(test_queens)
+            if len(test_queens) == BOARD_SIZE:
+                return test_queens
+            else:
+                return add_queen(test_queens)
+        except BailOut:
+            pass
+    raise BailOut
+
+queens = add_queen([])
+print (queens)
+print ("\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens))
